This invention relates to exhaust gas control valves for use in an automobile engine, and particularly to actuating rods for connecting such control valves to the throttle linkage of the engine.
The inventor's prior U.S. Pat. No. 3,989,018, which is incorporated herein by reference, discloses an exhaust gas control valve which is interconnected with an engine throttle by an actuating rod. Such a control valve is useful for reducing nitrous oxide emissions in motor vehicles. When a portion of the engine exhaust gas is supplied to the engine intake manifold, the inert characteristics of the exhaust gas tend to reduce peak combustion temperatures in the engine. Reduced peak combustion temperatures results in a lower level of undesired nitrous oxide emissions.
As indicated in U.S. Pat. No. 3,989,018, it is desired that the portion of exhaust gases supplied to the intake manifold be varied in accordance with the throttle setting. The exhaust gas return valve has a closed position when the engine is idling, opens as the throttle is advanced and then closes again at full throttle against a stop. In order to permit full throttle actuation after the exhaust gas valve reaches its stop position, it is necessary to provide for resilient expansion of the actuating rod interconnecting the throttle with the exhaust gas valve. Resilient connection is also desirable in the event that the exhaust gas return valve becomes jammed on account of icing or contamination from exhaust gas deposits. By providing a resilient spring in the force transmitting direction of the actuating rod, it is possible to operate the throttle of the engine while the valve is jammed in a closed position.
The prior patent discloses an actuating rod which provides resilient interconnection of the exhaust gas control valve and the throttle. The rod therein disclosed includes first and second rod portions which are in force transmitting interconnection by use of a spring. The first rod portion has a tubular section which is arranged coaxially around the second rod portion. The spring is arranged surrounding the tubular section. There is additionally provided an adjusting nut, functioning as a turnbuckle, which is useful for adjusting the length of the actuating rod and therefore the setting of the exhaust gas control valve.
The actuating rod described in U.S. Pat. No. 3,989,018, while being fully functional for its intended purpose, is rather expensive to manufacture in large quantities for use on automobiles. The inventor's prior U.S. Pat. No. 4,018,098, granted on Apr. 19, 1977 discloses a less expensive actuating rod which is fabricated from a pair of rods, one of which is bent to form a loop surrounding the other.
While both of these prior actuating rods are useful for connecting control valves to the engine throttle linkage, they both contain a hexagonal adjusting nut for modifying the total length of the actuating rod. The use of a hexagonal nut makes it difficult to ascertain the position of the adjusting mechanism. This is particularly true when the actuating rod is located in an awkward or difficult to view position on the vehicle engine.
It is an object of the present invention to provide a new and improved actuating rod which may be easily adjusted without the need to view the rod during the adjustment process.
It is a further object of the invention to provide such a rod which is inexpensive to manufacture in large quantities.